Where does “নতুন” come from?

নতুন (Bengali) comes from Sanskrit नूतन, from Sanskrit न, from Proto-Indo-Iranian ná, from Proto-Indo-European né — not; no.

নতুন (Bengali): new

Definitions

Step	Language	Word	Meaning
1	Sanskrit	नूतन	current, modern; new, fresh, novel, young
2	Sanskrit	न	no, not; no, not, none, no one, nothing, never,...
3	Proto-Indo-Iranian	ná	no, not
4	Proto-Indo-European	né	not; no

নতুন — Etymology, Origin & Word History | Etymology Explorer